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Caravaggio

Michelangelo Merisi da Caravaggio (1571 - 1610) was an Italian artist active in Rome, Naples, Malta, and Sicily between 1592 and 1610. His paintings, which combine a realistic observation of the human state, both physical and emotional, with a dramatic use of lighting, had a formative influence on Baroque painting.

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The Cardsharps (1594)**

The Cardsharps (painted around 1594) is a painting by the Italian Baroque artist Michelangelo Merisi da Caravaggio.

The painting shows an expensively-dressed but unworldly boy playing cards with another boy. The second boy, a cardsharp, has extra cards tucked in his belt behind his back, out of sight from the mark but not the viewer, and a sinister older man is peering over the dupe's shoulder and signaling to his young accomplice. The second boy has a dagger handy at his side, and violence is not far away.
Source:
Wikipedia, Cardsharps (Caravaggio).

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Golden rectangle**

A golden rectangle
is a rectangle whose side lengths are in the golden ratio,
one-to-phi, that is, approximately 1:1.618. A distinctive
feature of this shape is that when a square section is
removed, the remainder is another golden rectangle, that is,
with the same proportions as the first. Square removal can
be repeated infinitely, which leads to an approximation of
the golden or Fibonacci spiral.

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Droste Effect**

The Droste effect is a specific kind of recursive picture, one that in heraldry is termed mise en abyme. An image exhibiting the Droste effect depicts a smaller version of itself in a place where a similar picture would realistically be expected to appear. This smaller version then depicts an even smaller version of itself in the same place, and so on. Only in theory could this go on forever; practically, it continues only as long as the resolution of the picture allows, which is relatively short, since each iteration geometrically reduces the picture's size. It is a visual example of a strange loop, a self-referential system of instancing which is the cornerstone of fractal geometry.
Source:
Wikipedia,
Droste Effect.